Feline Small Cell Lymphoma

FelixHistory & Pre-diagnosis

Spring 2007 was a tumultuous time. In March we adopted an older kitten to keep Felix company. Felix and the kitten got along well, but the kitten was very energetic compared to my 13 year old boy. Just a few days after getting the kitten, we took both of them to the vet for checkups. The vet said Felix had a heart murmur and recommended we see a cardiologist.

This was also the time when the large-scale melamine-tainted pet food recall occurred, which included the canned food Felix ate. His appetite hadn't been good lately and he wasn't eating much canned food, so we were not too concerned that he had ingested a possible contaminant.

But by April, it was clear that Felix was not his usual energetic self. He felt thinner so I weighed him. Ever since he was 1 year old, Felix weighed 9 pounds plus an ounce or two. He had lost nearly 1 pound (he was now 8lb-3oz), and although that doesn't sound like much, it was over 10% of his body weight for a cat whose weight hadn't changed for 12 years. We didn't know if the weight loss was due to the increased activity from having a new kitten, because we stopped feeding his canned food, or if it was related to his newly-detected heart murmur. We decided everything was proving to be much for him, and we returned the kitten to its foster organization so we could focus on trying to keep our boy healthy. In July, Felix's heart murmur was determined to be due to hypertrophic cardiomyopathy, but it was not causing him any problems.

Over the next several months we monitored Felix's health. By September his weight was up to 8lb-11oz, but then it started to go down again. By February 2008, his weight was back down to 8lb-3oz. I knew something wasn't right - there was no reason he should be losing weight. But there we no obvious signs of illness – no vomiting or lethargy, and just a few minor instance of loose stool. He just had a decreased appetite and was getting too thin. We we took him to the vet and they ran a complete blood panel with thyroid hormone check (normal), urinalysis (normal) and infectious disease tests (FeLV, FIV, FIP, Toxoplasmosis) all of which were negative. An ultrasound showed he had some mild thickening of the intestinal wall that might indicate IBD. Since there were no obvious signs of disease that warranted us doing more invasive tests, the vet recommended we observe him for 6 months and come back for another ultrasound.

It was only 2 months later that Felix had a serious problem.

Diagnosis

April 2008, just a few days after his 14th birthday, Felix was admitted to the hospital with an intestinal obstruction. It was a fecalith, which is a hard mass of feces. For some reason his stool formed a large, solid mass and was not moving along the intestines. After 2-1/2 days in the hospital the fecalith finally passed.

The ultrasound taken during his hospitalization showed that the thickening of his intestines had worsened. The internist recommended we obtain biopsies of the small intestine to make a diagnosis and treatment plan. We had two options for the biopsy. First was to do full-thickness biopsies that required surgery through the abdomen. This would insure the pathologist had the tissue sample needed to make a diagnosis but this method also came with the risk of the biopsy site not healing properly. Our second option was to do surface biopsies through endoscopy. There was a slim chance that the tissue would not be enough "thickness" to make an accurate diagnosis, and the slight risk of perforating the intestine during the biopsy. Since Felix was already stressed and weakened from the hopsitalization, I did not want to put him through a full surgical procedure and the more serious associated risks. So I decided to proceed with the endoscopic biopsies.

Endoscopic biopsies of his stomach and duodenum (small intestine) were sent to a pathologist who diagnosed small cell lymphoma.

Treatment

We started Felix on a standard teatment protocol of prednisolone and chlorambucil. About 80% of cats with small cell lymphoma respond to these drugs, and many live for years with treatment. Unfortunately, Felix fell into the category of cats who do not respond to this treatment. For several months we tried increasing the dose of the drugs, without much effect. His weight slowly crept downward and we added an appetite stimulant (cyproheptatdine) to his treatment. This increased his appetite, but the disease continued to progress and he continued to slowly lose weight.

By October he was only 7 pounds and we knew we didn't have many options remaining. The vet suggested we try a different chemotherapy drug, lomustine. She had some success with it, and it wasn't supposed to make Felix feel terrible. That was one of my main concerns at this point – that if we tried something different, Felix's quality of life would not be decreased and he wouldn't feel terrible from chemotherapy drugs. One of the side effects of this drug is that it can suppress the immune system and cause a low white blood cell count. But the cells regenerate, and we'd just have to adjust the timing of the medication to what his system would tolerate. Unfortunately, Felix had a severe adverse reaction to the first dose of Lomustine. After 7-10 days he was low energy and not eating quite as well as the week before. His eyes were a little irritated, but I thought it was because a few of the little hairs around his eyes had fallen out and maybe irritated his eyes. The second week was similar to the first, but one night he seemed to be breathing a bit louder as he exhaled. We watched him closely the next day, and that night his breathing became more labored. We took him to the hospital and they told us both his white and red blood cells were almost completely wiped out. His irritated eyes were probably due to some sort of upper-respiratory tract infection. They said he needed to be hospitalized for a transfusion and we'd have to delay his next dose of lomustine.

But we decided our little boy had gone thought enough. We didn't want to leave him in the hospital for treatment, only to know that he'd likely have another problem in another week or so. We decided it was time to help him go, and the vet euthanized our Precious as we held him in his favorite blanket.

Looking Back

In hindsight, Felix had been losing weight for almost 1 year before his small cell lymphoma was diagnosed. The gradual loss of weight was probably due to the disease, and not other factors (new cat, new food). Other than a few bouts of mild diarrhea, there were no obvious signs early on that he was ill. The first indication we had that something was seriously wrong is when his bowel became obstructed. We may have been able to get a diagnosis a little earlier, but I don't think the outcome would have been different since he was one of the cats that did not respond to standard treatment.